dataframe_parser: use pre tag for table data

[utkarshgupta137]

Description

DataFrame may contain some data which may get parsed to MathJax elements which don't play nicely with tables & may not properly represent the actual dataframe data. To avoid this, we can wrap the data in <th>/<td> tags in <pre>.
I've also added a couple of style unsets to fix formatting issues.

Checklist

• Wrote a description of my changes above
• Formatted my code with black
• Added a bullet point for my changes to the top of the CHANGELOG.md file
• Added or modified unit tests to reflect my changes
• Manually tested with a notebook
• If adding a feature, there is an example notebook and/or documentation in the README.md file

[devstein]

Hey @utkarshgupta137 thanks for making a PR. Do you have a code snippet I can use for manual testing?

[utkarshgupta137]

Hey @utkarshgupta137 thanks for making a PR. Do you have a code snippet I can use for manual testing?

I've switched jobs & don't have access to a Spark Cluster, but you should be able to reproduce this with non-ASCII text. AFAIR Indic languages were causing issues.